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THE  LIBRARY 

OF 

THE  UNIVERSITY 

OF  CALIFORNIA 


PRESENTED  BY 

PROF.  CHARLES  A.  KOFOID  AND 

MRS.  PRUDENCE  W.  KOFOID 


v/rum 


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THE 


Gape  Worm  of  Fowls 


( Syngamus  trachealis ); 


(Lumbricas  terrestris), 

ITS  INTERMEDIATE  HOST. 


ALSO, 

On  the  Prevention  of  the  Disease  in 

Fowls  called  the  Gapes,  which 

is  Caused  by  this  Parasite. 


i%V 


OEOID, 

=7=  RY, 


U  [>  ■ 


BY 

FRANKL1NVILLE,  N.  Y. 


THE 


Gape  Worm  of  Fowls 

(Syngamus  trachealis); 

THE    KARTHWORM 

{Lumbricus  terrestris), 
ITS  INTERMEDIATE  HOST. 

ALSO, 

On  the  Prevention  of  the  Disease  in  Fowls 

Called  the  Gapes,  which  is  Caused 

by  this  Parasite. 


By  H.  D.  WALKER,  M.  D., 


FRANKLINVILLE,  N.  Y. 


COPYRIGHTED   BY 

DR.  H.  D.  WALKER,  Franklinville,  N.  Y., 

AND 

J.  Y.  BICKNELL,  Buffalo,  N.  Y. 
189  7. 


SYNGAMUS  TRACHEALIS. 

EXPLANATION  OP  FIGURES. 

Fig.  1— Adult,  male  and  female  Syngamus,  united  (natural  size  and  enlarged  12  diameters). 
A,  male;  B,  female,  each  showing  the  head,  esophagus  and  intestine.  In  the  female 
may  be  seen  the  uterus  and  ovarian  tubes  filled  with  eggs.    In  the  male,  the  seineniferous 

tube. 

Fig.  2.— Smallest  pair  of  Syngami  ever  seen  (enlarged  50  diameters).    A,  male;  B,  female. 

Fig.  3.— Embryo  of  Syngamus  removed  from  the  earthworm  and  kept  in  the  blood  serum  of 
a  calf,  in  an  incubator,  at  105°  Fahr.,  between  four  and  five  days.  About  moulting  the 
second  time  after  being  placed  in  the  serum.  Embryo  lying  within  the  exuviae.  See 
structure  of  mouth  of  embryo,  and  also  in  the  exuviae  (enlarged  200  diameters). 

Fig.  4.— Embryo  of  Syngamus  removed  from  the  earth  worm  and  kept  in  the  blood  serum  of 
a  calf,  in  an  incubator,  at  105°  Fahr.,  for  24  hours.  About  moulting  the  first  time  after 
being  placed  in  the  serum  (enlarged  200  diameters). 

Fig.  5.— Embryo  of  Syngamus  removed  from  the  lung  of  a  chick  fed  earthworms  containing 
the  embryos.    This  embryo  had  just  entered  the  lung  (enlarged  200  diameters). 

/7„  6.— Embryo  of  Syngamus  removed  from  the  intestinal  canal  of  an  earthworm  (enlarged 
200  diameters). 

jJ7ff-  7.— Embryo  of  Syngamus  within  the  egg  < enlarged  200  diameters). 

Fig.  8.— Egg  of  Syngamus  in  the  mulberry  state  (enlarged  2li0  diameters). 

jrtc,.  <». — Perfect  egg  of  Syngamus  immediately  after  passing  out  of  adult  female  (enlarged 
200  diameters). 

/,•,„_  id— Caudal  pouch  of  male.  Observe  the  eight  principal  ribs  which  are  subdivided  SO 
there  are  eighteen  divisions  at  the  circumference,  each  extremity  of  which  i>  expanded 
into  a  sucker.  These  suckers  project  through  the  broad  margin  of  the  pouch  which  is 
closely  applied  around  the  vulva  of  the  female,  to  which  they  enable  it  very  firmly  to 
adhere.  The  posterior  part  of  the  circumference  of  the  pouch  is  cut  out  and  has  no  suck- 
ers.   Here  is  where  the  eggs  pass  out. 


15354637 


PREFACE. 

Fourteen  years  having-  elapsed  since  I  first  commenced  the 
study  of  the  gapes  in  fowls,  it  cannot  be  asserted  that  the  con- 
clusions now  arrived  at  are  hasty  and  have  not  stood  the  test 
of  time  and  mature  consideration.  My  first  paper  on  the  sub- 
ject was  read  before  the  Buffalo  Microscopical  Club,  November 
nth,  1884.  In  1886  I  published  a  paper  in  the  Bulletin  of  the 
Buffalo  Society  of  Natural  Sciences,  Vol.  V.,  No.  2.  The  pres- 
ent publication  is  a  revision  of  that  paper,  with  extracts  from 
articles  written  for  various  journals,  and  additional  matter  here- 
tofore unpublished  in  regard  to  the  life  history  of  the  parasite 
causing  the  gapes.  The  illustrations  are  from  drawings  made 
by  Mrs.  Helen  M.  Judd  from  microscopic  slides.  I  send  forth 
this  small  pamphlet  with  the  earnest  desire  that  science  and  the 
poultry  and   game  bird  raisers  throughout  the  world  may  be 

benefitted  thereby. 

H.  D.  WALKER. 
Franklinville,  N.  Y.,  November,  1897. 


INTRODUCTION. 

In  the  following  pages  we  present  the  results  of  experiments 
made  for  the  purpose  of  determining  the  intermediate  host  of 
the  gape  worm  of  fowls.  We  have  endeavored  at  the  same  time 
to  trace  out  the  life  history  of  this  parasite,  in  its  various  stages 
from  the  egg  to  the  perfect  worm,  also  to  devise  means  for  the 
prevention  of  the  disease  caused  by  it  among  fowls. 

The  object  of  undertaking  the  work  was  two-fold.  First,  it 
was  thought  if  its  intermediate  host  could  be  discovered  the 
disease  might  be  prevented  to  a  great  degree,  and  much  good 
result  therefrom.  Second,  the  love  of  original  investigation  and 
a  determination  to  work  out  the  life  history  of  this  parasite, 
which,  although  well  known  in  its  mature  condition  in  the 
trachea  of  fowls  for  about  one  hundred  years,  had  thus  far,  in  its 
embryonic  state  in  nature,  remained  unknown.  The  work  has 
been  exceedingly  difficult,  for  several  reasons.  When  the  inves- 
tigation was  begun,  I  knew  nothing  about  Entozoa.  Microscop- 
ical work  was  also  comparatively  new.  Living  in  a  small  vil- 
lage, I  had  no  public  libraries  to  consult,  and  was  dependent  for 
the  literature  of  the  Entozoa  on  a  few  books  which  I  procured 
during  the  investigation.  My  profession  also  left  me  little  leisure, 
and  the  most  of  this  work  has  been  done  at  such  odd  times  as  I 
could  spare  from  other  duties.  I  wish  here  to  express  my  thanks 
to  that  eminent  naturalist,  the  late  Dr.  Joseph  Leidy,  of  Phila- 
delphia, for  many  favors  in  inspecting  my  microscopic  slides,  and 
for  advice  and  encouragement  in  the  work.  Valuable,  indeed, 
were  the  services  he  rendered  me.  I  am  under  obligations  to 
Lord  Walsingham,  of  England,  for  books  to  aid  in  the  investi- 
gation. Friends  in  the  Buffalo  Microscopical  Club,  and  neigh- 
bors have  also  assisted  me  in  various  ways.  I  have  freely  con- 
sulted Dr.  T.  Spencer  Cobbold's  work  on  "Parasites,"  also  Pro- 
fessor L.  G.  Neumann's  treatise  on  "Parasites  and  Parasitic  Dis- 
eases of  Domesticated  Animals,"  and  Dr.  Pierre  Megnin,  "On 
the  Gapes  Disease  in  Gallinaceous  Birds."  Finally,  I  trust  these 
pages  will  not  be  scanned  with  too  critical  an  eye,  for,  doubtless, 
imperfections  will  be  found.  I  can  only  say  that  I  have  honestly 
endeavored,  according  to  the  best  of  my  ability,  to  place  before 
the  reader  the  life  history  of  one  of  the  humblest  of  creatures,  a 
worm,  but  which,  nevertheless,  plays  well  its  own  part  in  this 
world  of  animated  nature. 


ZOOLOGICAL  CLASSIFICATION  AND  HABITAT. 

The  Animal  Kingdom  is  divided  into  several  sub-kingdoms. 
One  of  these  is  called  Worms  (Vermes).  This  sub-kingdom  is 
separated  into  classes,  one  of  which  is  named  Round  Worms 
(Ncmatliclminths).  Another  division  into  orders  is  made,  among 
which  are  the  Nematode  Worms  (Nematodes).  This  order  con- 
tains, among  other  genera,  that  of  Syngamus,  which  is  repre- 
sented by  two  species,  Syngamus  bronchialis  and  Syngamus 
trachcalis,  the  last  of  which  is  the  subject  of  our  present  work.* 

Another  name  for  this  worm  is  Sclcrostoma,  or  Strongylus 
syngamus.  Syngamus  trachcalis  is  stated  to  have  been  found  in 
the  trachea  of  the  turkey,  domestic  fowl,  pheasant,  partridge, 
black  stork,  magpie,  hooded  crow,  green  woodpecker  and  star- 
ling.    I  have,  myself,  found  it  in  the  robin,  and  believe  most  if 

not  all  worm-eating  birds  serve  as  a  host  for  this  parasite. 
■* 
HISTORICAL  REFERENCE. 

The  first  public  record  of  the  Gapes  was  made  by  Dr.  Wiesen- 
thall,  Professor  of  Anatomy  at  Baltimore,  Md.  In  a  communica- 
tion dated  May  21st,  <  1797,  and  published  in  the  Medical  and 
Physical  Journal  in  1799,  he  says:  "There  is  a  disease  prevalent 
among  the  gallinaceous  poultry  in  this  country  called  the  gapes, 
which  destroys  eight-tenths  of  our  fowls  in  many  parts,  and  is 
most  prevalent  among  young  turkeys  and  chickens  bred  upon 
established  farms.  Chicks  and  poults,  in  a  few  days  after  they 
are  hatched,  are  frequently  found  to  open  wide  their  mouths 
and  gasp  for  breath,  at  the  same  time  sneezing  and  attempting 
to  swallow.  At  first  the  affection  is  slight,  but  gradually  becomes 
more  and  more  oppressive,  and  ultimately  destroys;  very  few 
recover;  they  languish,  grow  dispirited,  droop  and  die.  It  is 
generally  known  that  these  symptoms  are  occasioned  by  worms 
in  the  trachea.  I  have  seen  the  whole  windpipe  completely  filled 
with  these  worms,  and  have  been  astonished  at  the  animal's  being 
capable  of  respiration  under  such  circumstances."  The  above 
is  a  truthful  description  of  the  disease  as  it  prevails  in  this  coun- 
try to-day.  In  1808,  Mr.  George  Montagu  gave  an  account  to 
the  Wernerian  Society  of  a  species  of  Fasciola.  which  infests 
the  trachea  of  poultry,  with  a  mode  of  cure.  This  led  to  its  being 
noticed  in  the  systematic  works  of  the  day.     Dr.  Cobbold,  from 


•The  aame of  the  genus  Syngamus  is  derived  from  two  Greet  words,  o  »  0,  with,  together, 

andy«uo«,  marriage,  and  1ms  icl'ercnee  In  the  peculiar  union  of  the  sexes. 


whose  work  on  parasites  this  brief  history  was  taken,  has  made 
some  observations  on  this  worm.  In  1879,  Lord  Walsingham, 
of  England,  offered  a  prize  of  two  hundred  and  fifty  dollars,  to 
be  awarded  by  the  Council  of  the  Entomolpgical  Society  of  Lon- 
don, for  the  best  essay,  comprising  a  complete  life  history  of 
the  parasite  causing  the  gapes.  Mr.  Charles  Black  and  Dr. 
Pierre  Megnin,  a  well-known  French  scientist,  competed  for  the 
prize.  The  latter  received  the  award.  The  conclusions  at  which 
he  arrived  in  regard  to  the  propagation  of  the  disease  are  as  fol- 
lows: First,  that  birds  pick  up  mature  Syn garni  filled  with  eggs, 
which  are  coughed  out  by  those  having  the  disease,  or  the  eggs 
are  taken  in  their  food,  or  the  embryos  after  they  are  hatched  in 
water,  and  they  are  developed  within  them  to  the  perfect  form. 
Second,  that  no  intermediate  host,  as  perfect  insects,  larvae,  mol- 
lusks,  or  any  other  living  agent,  has  any  share  in  spreading  the 
disease.  In  a  supplement  to  the  above,  after  discovering  a 
nymph  of  Syngamus  in  the  pulmonary  tissue  of  a  red  partridge, 
he  says:  "In  the  preceding  memoir,  written  about  twenty  months 
ago,  we  pointed  out  that  the  eggs  ejected  during  the  coughing 
fits  hatch  in  the  water,  and  that  the  embryo,  resembling  an 
anguillula,  may  live  in  this  medium  for  many  months,  because 
we  have  kept  some  alive  almost  a  year,  in  a  low  temperature. 
The  birds  are  infected  by  drinking  the  water  containing  these 
embryos.  But  how  are  they  developed  in  the  body  of  birds, 
and  in  what  way  do  they  reach  the  trachea,  where  they  are  found 
in  the  adult  stage,  fixed  to  the  mucous  membrane,  like  leeches, 
the  two  sexes  united  in  a  permanent  manner,  and  the  females 
crowded  with  eggs?"  He  closes  the  supplement  as  follows: 
"This  discovery  of  the  nymph  enables  us  to  say  that  all  the 
developmental  phases  of  Syngamus  trachealis  are  now  known. 
The  only  two  media  which  this  parasite  inhabits  during  its  entire 
existence  are  the  water  or  moist  earth  during  its  embryonal  con- 
dition, and  the  respiratory  organs  of  its  victim  during  its  nymphal 
and  its  adult  phase.  It  is  developed  without  the  aid  of  any  other 
medium  than  the  water,  corresponding  in  this  respect  to  the  im- 
mense majority  of  verminous  parasites."  This,  then,  is  the  con- 
clusion at  which  Dr.  Megnin  arrives,  after  five  or  six  years'  study 
of  the  gapes  in  the  various  pheasantries  of  Central  France,  and 
around  Paris.  Dr.  Cobbold  says,  in  his  work  on  "Parasites," 
page  445:  "A  change  of  hosts  is  probably  necessary,  but  in  the 
first  instance  they  either  enter  the  substance  of  fungi  or  other 


8 

vegetable  matters,  or  they  bury  themselves  in  the  soil  a  short 
distance  from  the  surface."  In  Lord  Walsingham's  preface  to 
the  essay  by  Dr.  Megnin,  he  says:  "By  Dr.  Megnin's  permis- 
sion, his  memoir  is  now  published  in  a  separate  form,  the  sub- 
ject of  it  being  one  which  could  not  rightly  be  included  amongst 
the  publications' of  the  Entomological  Society,  although  at  the 
time  of  offering  the  prize  I  was  led,  by  information  gathered  from 
various  sources,  to  think  it  possible  that  the  larvae  of  some  insect 
acted  the  part  of  host  to  the  embryonic  form  of  Syngamus."  Dr. 
Joseph  Leidy  believed  the  embryos  would  be  found  in  some  in- 
termediate host.  The  above  comprised  our  knowledge  on  the 
subject  when  this  research  was  begun. 

PRESENT  INVESTIGATION. 

The  present  investigation  was  commenced  during  the  summer 
of  1883.  Great  numbers  of  young  poultry  dying  of  the  gapes, 
some  of  my  neighbors  applied  to  me  for  aid  to  arrest  the  disease. 
Knowing  very  little  about  the  gapes,  but  having  heard  it  was 
caused  by  worms  in  the  trachea,  I  made  a  careful  examination 
of  their  windpipes,  and  found  numbers  of  the  worms  attached 
thereto  by  their  sucker-like  mouths.  Never  having  studied  the 
Entozoa,  and  having  no  works  on  them,  I  sent  a  specimen  to 
Dr.  Joseph  Leidy,  of  Philadelphia,  asking  him  its  name,  and 
where  I  would  find  information  on  the  subject.  He  kindly  re- 
plied, and  referred  me  to  Dr.  Cobbold  on  "Parasites,"  and  an 
article  by  Dr.  N.  H.  Paaren,  in  the  American  Entomologist,  Vol. 
2,  page  149.  I  immediately  procured  these,  and  reading  the  ar- 
ticles on  that  subject,  could  find  nothing  regarding  its  origin. 
I  therefore  again  addressed  Dr.  Leidy,  asking  him  for  the  de- 
sired information.  On  August  15th,  1883,  I  received  his  reply 
as  follows:  "The  source  of  the  gape  worm  (Syngamus  trachealis), 
of  chickens,  has  not  been  discovered.  If  you  have  an  opportunity 
of  investigating  and  determining  its  origin,  you  may  do  much 
service  to  science.  It  would  be  found  only  in  the  embryonic 
or  larval  condition,  in  some  intermediate  host."  I  thought  this 
was  not  only  a  good  field  for  microscopic  examination,  but  also 
one  which,  should  I  succeed  in  the  work,  would  be  productive 
of  much  good.  Therefore,  I  commenced  an  investigation  of  the 
coops  and  their  vicinity,  where  the  chicks  suffered  must  from  the 
gapes.  About  these  I  found  three  not  improbable  sources  of  the 
disease:     First,  the  common  earth  worm   (I.iimbriats  terrestrls) ; 


9 

second,  the  sow  bug  (Oniscus  ascllus);  third,  the  garden  slug 
Limax  Havus).  My  attention  was  especially  directed  to  one  coop 
where  the  chicks  all  had  the  gapes.  This  was  placed  on  a  grassy 
plot,  but  close  by  its  side  was  a  small  space  of  bare  ground,  a 
few  inches  square.  It  seemed  quite  probable  that  here  was  the 
place  where  they  obtained  the  parasite,  so  I  dug  into  it  and  found 
it  full  of  earthworms.  I  took  some  of  these  home  and  exam- 
ined them  with  the  microscope,  as  I  did  also  Oniscus  and  Limax. 
I  found  that  both  the  slug  and  earthworm  contained  various 
kinds  of  parasites  in  abundance.  None  were  found  in  Oniscus. 
To  determine  which  one,  if  any  of  these,  was  the  intermediate 
host  of  Syngamus  trachcalis,  I  procured  some  young  chicks  from 
a  neighborhood  where  no  gapes  existed,  and  fed  each  separately 
to  the  chicks.  In  neither  of  the  chicks  fed  with  sow  bugs  or 
slugs  was  any  result  produced,  but  the  chick  fed  with  earth- 
worms developed  symptoms  of  the  gapes.  To  guard  against 
error,  all  the  chicks  were  kept  in  a  barn  where  they  had  no  access 
to  the  ground,  and  their  food  was  cornmeal  mixed  with  pure 
water. 

EXPERIMENTS    IN   FEEDING   EARTHWORMS. 

Exp.  i.  On  September  29th,  1883,  at  8:30  a.  m.,  a  marked 
chick,  about  one  week  old,  was  fed  ten  earthworms  from  the  bare 
spot  of  ground  by  the  side  of  the  coop  where  the  chicks  had 
the  gapes.  The  worms  were  carefully  washed  in  water  to  re- 
move all  the  dirt  adhering  to  them,  which  might  contain  the 
eggs  or  embryos  of  Syngamus.  On  October  6th,  at  7:30  a.  m., 
six  days  and  twenty-three  hours  after  the  feeding,  I  observed  the 
first  symptoms  of  the  gapes.  On  October  7th,  at  10:30  a.  m., 
eight  days  and  two  hours  after  feeding  the  chick,  and  twenty- 
seven  hours  after  the  first  symptoms  of  the  disease,  I  killed  it  and 
found  twenty-six  gape  worms.  Of  these  worms,  two  only  were 
found  in  the  trachea;  they  were  at  its  upper  part,  and  were  the 
largest.  Ten  or  twelve  of  them  were  in  the  pharynx.  The  re- 
mainder were  in  the  esophagus,  from  its  upper  part  half  way 
down  to  the  crop.  All  these  were  united  in  pairs,  except  one 
male  and  female. 

Exp.  2.  On  October  gth,  at  8  a.  m.,  another  chick,  a  little 
over  two  weeks  old,  was  fed  four  earthworms  from  the  same 
place,  with  like  precautions.  At  the  same  time  of  day  on  the 
10th  it  was  fed  six  worms.     On  the  nth,  12th,   13th,   14th  and 


IO 

15th  it  was  fed  ten  worms  daily.  At  the  same  time  from  the  first 
feeding,  a  little  less  than  seven  days,  it  had  the  gapes.  It  was 
killed  in  eight  days  and  twelve  gape  worms  found,  all  in  the 
trachea. 

Exp.  3.  November  13th  three  chicks,  two  days  old,  were  fed 
earth  worms  from  my  garden,  eight,  nine  and  ten  days,  respect- 
ively. No  symptoms  of  the  gapes  were  produced,  but  to  deter- 
mine positively,  the  one  fed  nine  days  was  killed,  and  no  gape 
worms  found.  This  experiment  shows  that  all  earthworms  do 
not  contain  the  embryo  of  Syngamus.  To  confirm  this,  earth- 
worms from  the  same  place  have  been  repeatedly  examined  with 
the  microscope,  and  none  of  the  embryos  found. 

Exp.  4.  Two  mature  Syngami  were  broken  in  pieces,  so  as 
to  free  the  eggs.  They  were  then  placed  on  the  surface  of  a  dish 
filled  with  dirt,  well  moistened  with  water.  After  two  weeks 
some  earthworms  were  placed  in  this  dish  and  allowed  to  remain 
ten  days.  Three  of  these  were  fed  to  a  chick,  which  was  care- 
fully watched  for  two  weeks.  No  symptoms  of  gapes  were  dis- 
covered. Evidently  the  embryos  had  not  obtained  access  to 
the  earthworms  in  sufficient  numbers  to  produce  the  disease  in 
chicks. 

Exps.  5  and  6.  On  December  13th,  two  chicks,  four  weeks 
and  four  days  old,  were  each  fed  six  earthworms  from  the  infected 
spot,  with  the  same  precautions  as  before.  On  the  14th,  15th 
and  1 6th  the  feeding  of  six  worms  was  repeated,  making  twenty- 
four  to  each  chick.  On  December  20th,  about  seven  days,  as 
before,  they  had  the  first  symptoms  of  the  gapes.  One  was  now 
killed,  and  twenty-two  Syngami  were  found.  On  December 
24th,  eleven  days  from  the  first  feeding,  the  other  was  killed,  and 
sixteen  f6und.  All  of  them  were  united,  and  in  the  trachea. 
None  were  found  in  the  lungs,  but  it  is  probable  they  were  there, 
and  want  of  experience  in  the  search  prevented  their  discovery. 

Exps.  7,  8  and  9.  On  April  21st,  1884,  fed  three  chicks,  two 
days  old,  each  five  worms  from  the  same  place  where  the  others 
were  obtained.  Repeated  the  feeding  on  April  22d,  23d,  24th, 
25th,  26th  and  27th.  On  April  28th,  about  seven  days  from  the 
first  feeding,  all  had  the  gapes.  One  was  now  killed  ami  Syngami 
found  in  the  trachea,  also  three  pairs  in  the  lower  part  of  the  left 
lung  and  one  pair  in  the  lower  part  of  the  right  lung.  Continued 
to  feed  the  two  remaining  chicks  earthworms  until  May  5th,  just 
two  weeks  from  the  first  feeding,  when  one  was  killed  and  the 


II 


lower  part  of  the  trachea  found  crowded  with  Syngami.  One  of 
these  measured  seven-eighths  of  an  inch  in  length,  and  two  or 
three  others  three-fourths  of  an  inch.  They  contained  fully  de- 
veloped eggs,  as  did  also  the  excretions  of  the  chick  just  before 
it  was  killed.  This  proves  that  the  embryo  of  Syngamus  in  the 
earthworm  is  developed  to  maturity  in  two  weeks  from  the  time 
it  obtains  entrance  to  the  chick.  The  last  chick  was  killed  seven- 
teen days  from  the  first  feeding,  when  in  articulo  mortis.  In  the 
lungs  of  each  of  those  killed  at  fourteen  and  seventeen  days  from 
the  first  feeding,  embryo  Syngami  were  found  in  various  stages 
of  development. 

Exp.  10.  On  July  16th,  fed  a  chick  ten  earthworms,  and  re- 
peated the  feeding  for  nine  successive  days.  The  gapes  observed 
on  the  seventh  day,  as,  usual.  On  July  26th,  ten  days  from  the 
first  feeding,  I  killed  this  chick  and  found  a  large  number  of 
Syngami  in  the  trachea,  and  also  the  embryos  in  different  stages 
of  growth  in  the  lungs. 

Exp.  11.  In  order  to  see  if  Dr.  Megnin's  theory  was  correct, 
that  the  eggs  would  develop  within  the  fowl,  I  fed  a  chick  about 
three  weeks  old,  on  July  29th,  three  perfect  Syngami,  containing 
many  thousands  of  eggs.  This  chick  was  carefully  watched  for 
five  weeks,  and  no  symptoms  of  gapes  observed.  That  this  re- 
sult is  correct,  we  have  additional  proof  in  exp.  8,  in  which  large 
numbers  of  perfect  eggs  were  found  in  the  excretions  of  the 
chick,  on  the  fourteenth  day  after  feeding  earthworms  containing 
the  embryos  of  the  gape  worm.  I  believe  however,  if  the  eggs 
should  in  any  manner  be  retained  so  as  to  hatch  before  they 
passed  into  the  proventriculus,*  the  gapes  would  be  produced, 
but  think  such  a  case  must  be  very  rare,  and  would  be  unlikely 
to  occur  unless  the  embryos  were  fully  developed  in  the  egg  be- 
fore they  were  taken  by  the  fowl. 

Exp.  12.  Three  young  robins  (Turdus  migratorius),  in  the 
nest,  were  fed  several  infested  earthworms  each,  daily  for  twelve 
days.  These  earthworms  were  taken  from  the  same  place  as 
those  given  the  chicks.  No  well  marked  symptoms  of  the  gapes 
were  observed.  Two  of  them  were  killed,  and  three  or  four  gape 
worms  found  in  the  trachea  of  each.  A  number  were  also  found 
in  process  of  development  in  the  lungs.  These  birds  live  almost 
entirely  on  earthworms  during  a  part  of  the  year,  and  I  wished 

*The  proventriculus  is  the  first  or  glandular  stomach  where  the  gastric  juice  is  secreted, 
the  gizzard  being  the  muscular  stomach  where  the  food  is  triturated. 


12 


to  know  whether  they  would  serve  as  a  host  for  the  parasite,  and 
thus  be  instrumental  in  spreading  the  disease  from  farm  to  farm. 
The  trachea  of  robins  differs,  in  its  size  and  anatomical  structure, 
from  that  of  poultry,  especially  at  its  lower  part,  where  the  last 
ring  dilates  and  forms  a  second  larynx.  Syngami  generally  col- 
lect from  the  lower  part  of  the  trachea  to  its  middle,  and  the 
gapes  is  simply  the  effort  of  the  bird  to  obtain  more  air  through 
this  passage,  which  is  obstructed  by  these  worms.  It  is  evident, 
therefore,  that  birds  which  have  a  larger  trachea  would  harbor 
a  greater  number  of  Syngami  without  suffering  from  the  gapes. 
We  see  this  is  the  case  in  chicks  after  they  are  several  weeks 
old,  for  Syngami  can  often  be  seen  in  their  windpipes  by  open- 
ing their  mouths  and  straightening  out  their  necks.  Several 
worms  can  thus  be  seen  in  large  chicks,  with  very  little  embar- 
rassment to  respiration.  It  is  also  not  improbable  that,  although 
the  embryos  may  penetrate  the  esophagus,  pass  to  the  lungs  and 
thence  to  the  trachea,  the  greater  part  may  be  coughed  up  and 
swallowed  before  they  are  able  to  obtain  a  hold  on  its  mucous 
membrane.  We  know  from  an  examination  of  chicks  that  very 
many  of  them  are  thrown  off  in  this  way. 

Exp.  13.  On  July  4th,  at  5  p.  m.,  fed  a  chick,  about  four 
weeks  old,  a  large  number  of  Syngami,  just  hatched,  by  turning 
the  water  containing  them  down  its  throat.  On  July  nth,  at  7 
p.  m.,  this  chick  commenced  to  have  the  cough  or  sneeze  char- 
acteristic of  the  gapes.  July  12th,  coughed  much  more.  On 
July  13th,  at  9  a.  m.,  eight  days  and  sixteen  hours  after  the  feed- 
ing, I  killed  this  chick  and  found  one  single  and  twenty-nine 
pairs  of  Syngami, 

Exp.  14.  On  August  14th,  at  7  p.  m.,  fed  a  young  robin,  just 
from  the  nest,  a  large  number  of  embryo  Syngami,  hatched  in 
water,  as  in  the  preceding  experiment.  It  was  kept  in  a  cage 
hanging  under  a  tree,  and  fed  by  the  old  bird.  August  22d. 
morning:  Robin  had  some  symptoms  of  the  gapes,  such  as  rapid 
breathing,  an  occasional  gape  and  shake  of  the  head,  and  was 
inclined  to  sit  on  its  perch,  instead  of  standing  up,  as  usual. 
August  23d:  Breathed  more  rapidly,  and  evidently  quite  ill.  Au- 
gust 26th:  Robin  continued  to  grow  weaker  and  breathed  more 
rapidly,  and  at  times  gaped,  but  the  gaping  was  not  as  promi- 
nent a  symptom  as  in  the  case  of  chicks.  The  robin  died  the 
morning  of  the  29th,  the  fifteenth  day  from  the  feeding.  (  to 
examination  three  fair  sized  Syngami  were  found  in  the  trachea. 


13 

not  enough  to  fill  it  up,  so  as  to  produce  much  gaping.  The 
rapid  breathing,  which  was  the  most  prominent  symptom,  was 
readily  accounted  for  by  extensive  deposits  in  both  lungs,  more 
especially  the  right.  The  lower  part  of  each  lung  was  affected, 
and  the  diseased  condition  doubtless  resulted  from  the  irritation 
of  the  parasites.*  Many  other  feeding  experiments  with  chicks 
have  been  made  in  different  years  since  the  above.  'All  of  them 
thoroughly  confirm 'the  foregoing  ones  in  every  respect,  and  it 
is  deemed  unnecessary  to  detail  them  here.  Experiment  13 
proves  that  the  embryo  of  Syngamus  does  not  have  to  pass 
through  an  intermediate  host  to  obtain  any  change  in  structure, 
or  increase  in  development,  that  the  earthworm  is  simply  a 
bearer,  in  which  it  lives  in  its  embryonic  condition,  and  through 
which  it  obtains  access  to  its  final  host,  the  fowl.  This  chick 
was  kept  in  the  barn  and  all  other  sources  of  the  disease  excluded, 
which  was  not  the  case  with  the  robin.  The  time  from  the  feed- 
ing to  the  production  of  the  disease  in  the  chick  was  the  same 
as  when  earthworms  were  fed,  which  is  good  evidence  that  it  is 
the  embryo  instead  of  the  egg  in  those  which  causes  the  disease. 
It  may  further  be  stated  that  in  the  examination  of  many  infested 
earthworms  I  never  yet  found  one  to  contain  the  eggs  of  Syn- 
gamus. In  dissecting  the  robin  I  found  an  embryo  just  emer- 
ged from  the  esophagus  into  the  lung.  It  was  a  short  distance 
above  the  proventriculus,  was  sexually  developed,  being  a  male, 
and  thus  affords  convincing  proof  that  they  enter  the  lung  this 
way.  In  a  chick  I  also  found  a  pair  of  Syngami  just  united,  on 
the  posterior  part  of  the  esophagus,  which  had  the  appearance  of 
having  been  penetrated  by  these  worms.  I  have  also  found  the 
embryo  lying  beneath  the  mucous  membrane  of  the  esophagus. 

ARTIFICIAL  CULTURE. 

Exp.  15.  On  September  23d,  1883,  a  mature  Syngamus  filled 
with  eggs  was  placed  in  a  small  glass  dish  with  a  little  water,  for 
the  purpose  of  observing  the  development  of  the  embryo,  the 
structure  of  the  young  worms  and  the  time  required  for  them  to 
hatch.  We  also  thought  that  by  comparison  in  this  way  they 
could  be  more  positively  identified  in  the  earthworm.     The  dish 


*This  condition  resulting  from  parasites  is  mentioned  by  Dr.  N.  II.  Paaren,  in  the 
American  Entomologist,  Vol.  2,  page  149;  also,  by  Dr.  George  M.  Sternberg,  from  M. 
Larrlaine,  in  an  article  on  the  "Production  of  Tuberculosis  by  Inoculation,"  in  the 
American  Journal  of  Medical  Sciences,  Vol.  LXXXIX,  page  18. 


14 

was  kept  covered  in  a  warm  room  (650  to  yo°  Fahr.),  and  occa- 
sionally placed  several  hours  in  the  sun.  On  October  14th,  three 
weeks  from  placing  them  in  water,  they  commenced  to  hatch. 

Exp.  16.  June  nth,  1885,  placed  two  mature  Syngami  in  a 
small  glass  dish  of  water,  and  kept  them  in  a  room  where  they 
were  not  exposed  to  the  direct  rays  of  the  sun.  On  June  28th, 
seventeen  days  from  the  time  they  were  placed  in  water,  they 
commenced  to  hatch. 

As  will  be  seen  from  the  above  experiments,  the  time  required 
for  the  eggs  to  hatch  varies  under  different  circumstances.  When 
they  have  been  mature  for  several  days  and  kept  moist  and  in  a 
moderately  warm  place  they  will  undergo  segmentation  and  the 
embryo  commence  to  form.  If  these  eggs  are  now  placed  in 
water  in  a  warm  place  it  will  take  but  a  short  time  for  the  em- 
bryos to  hatch.  Again,  eggs  kept  in  moderately  warm  water 
will  mature  their  embryos  much  quicker  than  those  kept  cooler. 

Exp.  17.  December  1st,  1884,  placed  several  embryos  found 
coiled  up  in  the  muscular  sac  of  the  segmental  organs  of  the 
earthworm,  in  a  small  glass  dish  of  water  and  kept  them  loosely 
covered,  in  a  warm  room.  These  embryos  were  thought  in  the 
beginning  of  the  investigation  to  be  those  of  SyHganuis,  and  this 
method  was  adopted  to  see  if  any  growth  or  development  of 
structure  would  take  place  in  water,  whereby  we  might  decide 
the  question.  In  from  five  to  seven  days  they  grew  to  many 
times  their  original  length,  and  were  developed  into  male  and 
female.  A  small  number  of  eggs  were  also  seen  in  different 
stages,  within  the  oviducts  and  scattered  about  the  bottom  of 
the  vessel.  These  worms  correspond  with  the  description  and 
figures  in  the  Micrographic  Dictionary  under  the  head  of  Augtiil- 
lulidiac,  and  are  thus  excluded  from  being  the  embryos  of  Syn- 
gamus. 

Exp.  18.  Several  embryos  taken  from  the  intestinal  canal  of 
the  earthworm,  where  they  were  found  surrounded  by  mucus, 
were  placed  in  a  glass  dish  of  water  and  kept,  as  in  the  fore- 
going experiment,  seven  days.  These  embryos,  after  a  few 
hours,  coiled  themselves  up  at  the  bottom  of  the  dish,  and  for 
the  most  part  of  the  time  remained  in  this  condition,  occasionally 
uncoiling  and  moving  about  a  short  distance.  No  growth  or 
development  of  structure  took  place.  These  embryos  correspond 
in  size  and  structure  with  those  hatched  from  the  eggs  of  Syn- 


i5 

gamus,  and  later  in  the  investigation  were  fully  identified  as  being 
the  same. 

Exp.  19.  Placed  several  embryos  from  the  intestinal  canal  of 
the  earthworm,  like  those  in  the  preceding-  experiment,  in  a  cov- 
ered glass  dish  of  water,  and  then  in  an  incubator,  and  kept  them 
at  1050  Fahrenheit  for  seven  days,  at  which  time  they  were  alive, 
but  no  change  of  structure  or  development  had  taken  place. 

Exp.  20.  One  pint  of  blood  from  a  calf  was  allowed  to  stand 
in  a  glass  fruit  jar  until  the  solid  portion  had  settled,  leaving  the 
serum  at  the  top.  On  May  5th,  at  9  a.  m.,  one  dram  of  this 
serum  was  placed  in  a  Syracuse  solid  watch  glass,  with  ground 
edges,  containing  twenty  of  the  last  described  embryos.  These 
embryos  had  been  kept  in  the  watch  glass  in  water  one  week, 
and  were  nearly  all  lying  quietly  coiled  up  about  its  center.  The 
most  of  the  water  was  removed  by  a  pipette  before  the  serum 
was  added.  As  soon  as  this  was  done  the  embryos  uncoiled 
and  became  quite  lively,  as  though  they  had  at  last  found  their 
natural  element.  The  watch  glass  was  placed  in  an  incubator, 
covered  by  another  one  with  ground  edges,  but  leaving  a  small 
space  for  air.  The  temperature  had  previously  been  regulated 
so  as  to  remain  at  1050  Fahr.  At  9  p.  m.,  on  examining  them 
with  the  microscope,  they  had  slightly  increased  in  size  and  were 
commencing  to  moult.  On  May  6th,  at  9  a.  m.,  they  were  again 
taken  from  the  incubator  and  examined,  when  the  process  of 
moulting  had  still  further  advanced.  At  4  p.  m.  I  found  them 
all  dead.    The  culture  fluid  had  become  putrid. 

Exp.  21.  May  7th,  4  p.  m.,  completely  satisfied  that  I  was 
on  the  right  track,  I  removed  four  more  embryos  from  an  earth- 
worm and  placed  them  in  another  portion  of  serum,  and  in  the 
incubator  as  before.  On  May  8th,  at  9  a.  m.,  removed  them  to 
another  watch  glass  containing  fresh  serum,  by  taking  them  up 
under  an  inch  objective  with  a  small  splinter  of  wood  whittled 
to  a  fine  point.  At  9  p.  m.  the  same  day  they  were  again  removed 
to  fresh  serum.  One  was  found  dead,  another  had  moulted,  and 
the  two  others  had  nearly  completed  that  process.  May  9th,  9 
a.  m.,  they  were  seen  to  have  increased  in  size,  and  were  removed 
to  another  portion  of  serum.  These  embryos  lived  between  four 
and  five  days  in  the  incubator,  and  were  about  moulting  the  second 
time.  They  were  sufficiently  developed  to  show  the  peculiar 
structure  of  the  mouth  of  Syngamus  trachealis.     One  of  them 


i6 

measured  .0139  inch  in  length,  and  the  exuvia,  in  which  it  still 
remained,  .0227  of  an  inch.    (See  figure  3.) 

Exp.  22.  Four  of  the  embryos  from  the  earthworm  were 
placed  in  one  dram  of  egg  albumen,  after  it  was  beaten  to  render 
it  fluid.  They  were  placed  in  the  incubator  as  before,  and 
changed  to  fresh  albumen  daily.  After  being  kept  in  this  wav 
six  and  one-half  days,  they  were  alive,  but  there  was  no  change 
in  their  structure  or  size,  or  any  appearance  of  moulting  percept- 
ible. Evidently  the  proper  food  for  their  metamorphosis  and 
growth  was  not  contained  in  this  fluid.  In  these  culture  exper- 
iments the  incubator  used  was  one  in  which  the  heat  could  not 
be  thoroughly  controlled.  It  is  believed  with  a  good  one  and 
more  experience  better  results  could  be  attained.  It  is  also 
thought  the  blood  serum  of  a  fowl  would  be  best  adapted  for 
this  purpose.  This  method  of  artificial  culture  of  animal  parasites 
is  believed  to  be  new,  and  if  varied  according  to  the  different 
circumstances  in  which  they  are  found  in  nature  will,  we  think, 
render  easy  the  solution  of  some  of  the  most  difficult  questions 
as  to  the  life  history  and  embryonic  forms  of  many  of  these 
creatures.  The  subject  is  of  great  importance,  for  large  num- 
bers of  both  human  beings  and  animals  perish  each  year  through 
their  agency.  Moreover,  it  is  not  far  removed  from  that  great 
question  which  occupies  so  prominent  a  position  before  the 
medical  profession  at  the  present  time.  I  refer  to  the  germ  the- 
ory of  disease.  The  one  is  an  animal,  the  other  a  vegetable  par- 
asite. The  method  of  artificial  culture  is  now  being  used  for 
working  out  the  latter;  I  see  no  reason  why  it  cannot  be  success- 
ful in  the  former. 

EMBRYOLOGY  AND  DEVELOPMENT  OE  SYNGAMUS. 

The  egg  is  formed  out  of  the  granular  material  seen  near  the 
extremity  of  the  ovarian  tubes.  It  is  shaped  into  small  round 
bodies  which  pass  down  towards  the  uterus,  within  the  horns  of 
which  they  are  supposed  to  become  impregnated,  and  receive  the 
hard  external  coat  called  the  shell.  Within  the  body  of  the  female 
Syngamus,  about  fourteen  days  after  its  entrance  into  the  fowl, 
are  found  several  thousand  eggs  in  various  stages  of  develop- 
ment, from  the  granular  material  of  which  they  are  formed,  as 
it  exists  in  the  ovaries  and  ovarian  tubes,  to  the  perfed  egg  in 
the  uterus.     The  perfect  egg  is  oval,  about  .004  inch  in  its  long, 


17 

and  .0025  inch  in  its  short  diameter.  At  each  end  is  a  valve  or 
lid  which  drops  off  when  the  embryo  emerges  from  the  egg.  It 
has  been  the  general  opinion  among  naturalists  that  the  mature 
eggs  of  Syngamus  were  never  discharged  through  their  natural 
outlet  during  the  life  of  the  female,  that  being  rendered  impos- 
sible by  the  intimate  union  of  the  genital  organs  of  the  sexes, 
whereby  the  outlet  of  the  vagina  was  completely  closed.  They 
believed  that  only  at  the  death  of  the  worm  and  disintegration 
of  its  body  were  the  eggs  set  free.  That  such  is  not  the  case 
in  some  instances,  /  knoiv,  for  I  have  distinctly  seen,  under  the 
microscope,  with  a  power  of  fifty  diameters,  the  eggs  pass  out  at 
the  posterior  part  of  this  union  in  a  living  pair,  just  removed 
from  the  trachea  of  a  chick.  Two  or  three  eggs  were  discharged 
at  regular  intervals,  each  minute.  On  close  observation  there 
was  clearly  observed  movements  of  the  worm,  showing  the  nat- 
ural expulsive  efforts,  followed  by  the  extrusion  of  the  eggs. 
Now,  in  about  fourteen  days  after  the  feeding  of  earthworms1  con- 
taining the  embryos  of  Syngamus,  we  have,  in  several  later  exper- 
iments, some  of  which  are  not  herein  recorded,  observed  the  per- 
fect eggs  of  Syngamus  in  the  excretions  of  the  chicks.  These 
chicks  were  then  killed  and  the  living  pairs  of  Syngami  found 
attached  to  the  mucous  membrane  of  the  trachea.  Some  of 
these  pairs  had  not  yet  attained  their  complete  growth,  yet  the 
eggs,  near  the  genital  outlet,  were  fully  developed.  None  of 
them  were  found  dead  and  their  bodies  breaking  up  in  the 
trachea.  From  these  observations  we  have  no  doubt  that  the 
living  worm,  contrary  to  the  opinion  heretofore  entertained,  does, 
during  its  life,  extrude  a  large  number  of  perfect  eggs,  but  al- 
ways dies  while  many  yet  remain  in  its  body,  which  are  set  free 
when  that  decomposes.  I  have  never  been  able  to  press  the  eggs 
out  through  the  vagina  in  a  dead  Syngamus.  This  may  be  one 
reason  why  naturalists  have  thought  they  did  not  pass  out  when 
living  that  way,  but  I  believe  all  dead  animals  have  their  genital 
passages  contracted  in  the  same  manner.  It  has  also  been  the 
general  opinion  that  the  eggs  furthest  advanced  in  a  mature 
Syngamus  while  living  and  just  removed  from  the  trachea  of  a 
fowl  contain  the  perfect  embryo  already  moving  actively  about 
within  the  shell.  That  such  is  not  the  case  we  believe  and  will 
briefly  give  our  reasons  for  this  opinion.  In  experiment  No.  8, 
it  will  be  seen  that  a  chick  fed  earthworms  containing  the  em- 
bryos of  Syngamus  developed  the  gapes,  and  in  fourteen  days 


i8 

from  the  time  of  the  first  feeding  great  numbers  of  the  eggs  of 
Syngamus  were  found  after  they  had  passed  through  the  fowl's 
intestines.  These  eggs  passed  from  perfect  worms,  which  were 
found  attached  to  the  trachea  of  the  chick,  killed  the  same  day. 
Now,  the  eggs  which  passed  through  the  chick,  and  those  found 
about  the  perfect  worms  in  the  trachea,  showed  no  sign  of  em- 
bryonic formation.  Moreover,  we  will  say  that  after  the  exam- 
ination of  many  perfect  worms  removed  from  the  trachea,  we 
have  never  found  the  embryo  developed  within  a  single  egg  at 
that  time.  In  our  experience,  it  takes  these  eggs  not  far  from 
three  weeks,  varying  somewhat  with  the  temperature,  to  mature 
and  bring  forth  their  embryos.  We  believe  Syngami,  in  which 
active  embryos  wer»  found  within  the  egg,  had  been  for  many 
days  mature,  and  probably  kept  in  a  moist  condition,  either 
within  the  body  of  the  bird  or  external  to  the  same.  The  em- 
bryo of  the  lung  worm  of  calves  (Strongylus  micrurus),  is  fully 
developed  in  the  egg  while  in  the  lungs  of  the  calf.  Possibly, 
reasoning  by  analogy  has  had  something  to  do  with  this  opinion 
heretofore  entertained  concerning  Syngamus.  It  is  evident  the 
eggs,  scattered  over  the  ground  in  the  natural  way,  hatch  much 
quicker  during  the  hot  months  of  summer  than  later  in  the  sea- 
son. Indeed,  it  is  quite  probable  that  most  of  these  last  perish 
on  account  of  the  cold,  without  the  formation  of  an  embryo. 

DEVELOPMENT  OF  THE  EMBRYO. 

The  process  of  development  from  the  egg  is  as  follows: 
The  yolk  undergoes  segmentation;  that  is,  becomes  divided  into 
2,  4,  8,  etc.,  round  masses  or  spheres,  this  division  being  con- 
tinued until  it  assumes  the  mulberry  state.  The  embryo  is  devel- 
oped from  this  around  the  inner  part  of  the  shell,  in  the  form 
of  a  circle.  Before  it  emerges  the  embryo  usually  coils  itself 
within  the  egg,  like  the  figure  8,  from  which  it  generally  comes 
out  head  first.  The  time  required  for  the  perfect  egg  to  pass 
through  the  different  stages,  until  the  embryo  issues  from  it 
varies,  as  heretofore  stated.  On  one  occasion  a  few  of  the  em- 
bryos came  forth  in  seventeen  days.  The  embryo  on  emerging 
resembles  an  Anguillula,  but  its  movements  are  not  as  rapid  as 
most  of  the  worms  belonging  to  this  order.  It  is  about  .01 1  inch 
in  length,  and  .0005  inch  in  width  at  its  middle.  The  posterior 
half  of  the  body  is  filled  with  a  fine  granular  matter.     After  the 


19 

embryos  have  been  in  water  a  few  days  they  moult,  losing  about 
.0005  inch  in  length;  their  tails  are  then  more  blunt.  Sometimes 
they  pass  through  the  first  moult  while  coming  out  of  the  egg, 
leaving  the  old  skin  within. 

THE  EMBRYO  IN  THE  EARTHWORM. 

After  many  careful  microscopic  examinations  of  the  embryo, 
as  found  in  the  earthworm,  I  have  arrived  at  the  conclusion  that 
it  does  not  differ  in  its  structure,  so  far  as  can  be  discovered,  from 
the  embryo  which  hfis  passed  through  one  moult,  after  the  egg 
has  hatched  in  water.     The  method  of  finding  them  in  the  earth- 
worm is  as  follows:     Select  a  poultry  yard  where  chicks  have  had 
the  gapes  for  several  years,  so  that  the  earthworms  may  have 
plenty  of  the  parasites.     From  near  the  surface  of  bare  spots  of 
ground,  which  chicks  with  the  gapes  have  frequented,  take  some 
of  the  earthworms  and  examine  them  with  the  microscope.     The 
following  method  is  recommended:    Throw,  the  earthworm  to  be 
examined  into  a  solution  of  common  salt  (chloride  of  sodium), 
having  the  strength  of  about  two  ounces  to  the  pint  of  water. 
When  it  ceases  to  move,  rinse  in  pure  water;  then,  with  sharp- 
pointed  scissors,  slit  the  worm  its  entire  length.     Spread  out  on 
each  side,  to  expose  the  alimentary  canal.     In  order  to  intelli- 
gently proceed,  we  will   briefly  describe  the   organs   contained 
therein.     They  consist  of  the  mouth,  pharynx,  esophagus,  crop, 
gizzard  and  intestine.     Directly  connected  with  the  esophagus, 
about  its  middle  and  posterior  part,  are  found  six  white  bodies, 
three  on  each  side  called  the  esophageal  or  calciferous  glands. 
The  esophagus  passes  directly  into  the  crop,  which  is  just  in  front 
of  the  gizzard.     Following  this    is  the    intestine,    which    passes 
through  the  remaining  portion  of  the  worm.    We  cut  off  the  in- 
testine, just  back  of  the  gizzard,  and  taking  small  pieces,  about 
one-eighth  inch  long,  place  them  on  a  watch  glass  with  a  little 
water,  pick  them  well  in  pieces,  and  examine  carefully  with  an 
inch  objective.    We  generally  find  the  embryos  a  short  distance 
below  the  gizzard,  not  often  more  than  half  way  to  the  tail.    There 
are  numerous  kinds  of  parasites  which  inhabit  the  earthworm, 
some  of  them  numbering  thousands  in  a  single  worm.    We  have 
also  found  the  earthworms  in  different  localities  to  harbor  very 
different  kinds  of  parasites.     The  method  of  distinguishing  the 
embryo  of  Syngamus  is  its  size,  description  as  here  given,  and 


20 

general  appearance  as  seen  in  the  engravings.  We  believe  it  is 
taken  in  by  the  earthworm  with  its  food,  and  passes  down  into 
the  intestine,  where  it  remains  until  transferred  within  its  host  to 
the  digestive  organs  of  some  bird,  or  after  a  time  passes  through 
into  the  soil  and  perishes.  This  method  of  taking  in  the  embryo 
by  the  earthworm  is  the  common  law  in  nature,  through  which  all 
creatures,  man  included,  obtain  their  intestinal  parasites. 

THE  EMBRYO  OF  SYNGAMUS  IN  THE  FOWL. 

The  embryo  passes  into  the  crop  within  the  intestine  of  the 
earthworm.  We  wish  to  determine  at  what  point  it  leaves  the 
digestive  canal  and  passes  into  the  lungs  and  trachea  of  the  chick. 
We  have  never  been  able  to  trace  the  embryo  below  the  esopha- 
gus, after  many  examinations  of  chicks  dead  of  the  gapes.  If  we 
admit  that  they  do  not  pass  through  the  proventriculus  and  giz- 
zard alive,  which  I  have  no  doubt  is  the  truth,  there  are  only  two 
organs,  the  crop  and  esophagus,  through  which  they  could  gain 
admission  to  the  lungs.  The  crop  is  simply  a  dilatation  of  the 
esophageal  structures,  and  acts  as  a  reservoir  for  the  food.  We 
believe  the  embryo  passes  through  the  esophagus  just  above  the 
proventriculus,  for  the  following  reasons:  The  distance  to  the 
lung  structures  is  very  short,  only  the  thin  wall  of  the  esophagus 
intervening.  The  orifices  of  the  lenticular  glands  of  the  esopha- 
gus are  of  greater  diameter  than  the  embryo,  so  it  could  readily 
enter  through  them.  That  it  does  so  we  believe,  for  we  have 
found  them  beneath  its  mucous  membrane.  The  pulmonary 
bronchi  ramify  over  the  outer  surface  of  the  esophagus,  through 
the  substance  of  which  there  are  numerous  tubular  structures, 
which,  it  is  not  improbable,  may  be  connected  with  them.  We 
have  seen  the  embryo  just  emerged  from  the  esophagus  into  the 
lung,  and  have  in  all  the  chicks  carefully  examined  for  that  pur- 
pose, after  dying  of  the  gapes,  found  several  echymosed  spots, 
which  looked  as  though  the  embryos  had  passed  through.  We 
have  also  found  them  recently  united  on  the  outer  wall  of  the 
esophagus,  one  pair  being  the  smallest  we  ever  saw.  In  dissecting 
chickens  dying  of  the  gapes,  we  have,  many  times,  Found  the 
esophagus  adhering  to  the  lungs,  as  we  believe  from  the  inflam- 
mation caused  by  the  passage  of  the  embryos.  This  condition  of 
echymosis,  and  adhesion  of  the  esophagus  to  the  lungs,  we  have 
never  found  in  any  chicks  we  have  dissected  which  did  not  have 


21 

the  gapes.  Both  male  and  female  embryos  do  not  develop  beyond 
a  certain  point  until  union  takes  place.  After  this  they  pass  up 
into  the  trachea,  where  they  attach  themselves  to  the  mucous 
membrane  and  attain  maturity. 

ANATOMICAL    DESCRIPTION. 

We  shall  not  attempt  any  extended  anatomical  description  of 
Syugamits  trachcalis.  The  illustrations  accompanying  this  investi- 
gation will  show  its  appearance  in  the  different  stages  of  its  ex- 
istence. We  will  briefly  say  that  the  mouth  in  this  Genus  is  large, 
circular,  and  surrounded  by  four  outer  membranous  and  six  inner 
chitinous  lips.  The  young  worm  has  eight  inner  lips,  two  of 
which  uniting  with  two  others,  reduces  the  number  to  six  in  the 
adult  worm.  Within  it  is  hollowed  out,  and  contains  around  the 
opening  to  the  digestive  apparatus,  eight  lance-like  organs,  which 
are  supposed  to  pierce  the  mucous  membrane  for  extracting  the 
blood  of  its  host. 

THE  MALE. 

The  male  has  been  found  coupled  on  the  external  wall  of  the 
esophagus  of  the  chick  when  .035  inch  long,  and  .002  inch  wide. 
At  maturity  it  attains  the  length  of  about  .24  inch,  and  a  breadth 
of  about  .02  inch.  The  diameter  of  the  head  exceeds  that  of  the 
body,  which  is  round,  and  its  posterior  part,  containing  the  genital 
organs  and  anus,  is  united  to  the  anterior  part  of  the  vulva  of  the 
female  by  a  membranous  hood-like  organ,  called  the  caudal 
pouch.  This  organ  is  elongated  in  front,  with  about  one-third 
of  its  diameter  cut  out  on  its  posterior  part,  where  it  is  free  from 
the  female.  It  is  supported  by  eight  principal  ribs,  which  are  sub- 
divided as  follows:  The  posterior  ribs  on  either  side  are  double; 
next  to  these  on  each  side  they  are  trifid,  followed  by  a  single  rib, 
between  which  are  the  two  anterior  ribs,  also  trifid.  These  divi- 
sions of  the  ribs,  eighteen  in  number,  each  have  at  their  extremity, 
which  reaches  to  the  circumference  of  the  caudal  pouch,  a  disk 
or  sucker,  by  means  of  which  the  male  attaches  itself  to  the  genital 
organs  of  the  female  and  maintains  so  strong  a  hold,  that  even 
after  death  they  are  separated  with  much  difficulty.  There  is  no 
actual  growing  together  of  the  organs,  as  has  been  the  commonly 
received  opinion,  for  they  can  be  separated  entire  by  careful 
manipulation  in  diluted  glycerine.  Within  is  seen  the  digestive 
and  internal  genital  organs. 


22 

THE  FEMALE. 

The  female  has  been  found  united  with  the  male  on  the 
esophagus  when  .055  inch  long  and  .0025  inch  in  width,  and  in  its 
adult  state  sometimes  measures  .875  inch  in  length,  by  nearly 
.045  in  width.  It  is  of  a  bright  red  color  from  the  absorption  of 
the  hematin  of  the  blood  upon  which  it  lives.  When  mature  it  is 
irregularly  cylindrical,  curved,  and  often  variegated  by  the  white 
winding  uterine  horns  filled  with  eggs.  The  tail  is  conical  and 
just  in  front  of  its  extremity  is  the  anus.  The  vulva  is  a  short 
distance  back  of  the  head  and  is  attached  at  its  anterior  part  to 
the  caudal  extremity  of  the  male.  At  its  posterior  part  this  union 
is  incomplete,  the  perfect  eggs  passing  out  here  through  the 
vagina.    The  digestive  and  genital  organs  can  be  traced  within. 

PREVENTION  OF  THE  GAPES. 

The  very  best  results  which  can  be  attained  from  the  study  of 
disease  is  its  prevention.  If  the  only  way  in  nature  by  which  fowls 
contract  the  gapes  is  from  eating  earthworms  containing  the 
embryos  of  Syngamus,  it  follows  if  none  of  these  were  eaten  the 
disease  would  become  extinct.  We  believe,  after  many  years' 
study  of  the  gapes,  that  this  is  the  only  natural  way  in  which 
fowls  contract  the  disease,  but,  should  they  take  in  the  embryos 
in  any  other  way  the  disease  would  be  equally  liable  to  occur.  We 
have  never  observed  this  to  take  place,  and  believe  it  never  docs 
except  through  the  instrumentality  of  man.  Adopting  this  view, 
there  are  two  methods  of  prevention,  either  one  of  which  will 
prove  effectual.  First,  keep  young  fowls  from  the  ground  where 
earthworms  are  infested  by  the  embryos.  Second,  destroy  the  earth- 
worms containing  them,  when  the  fowls  could  be  allowed  their 
liberty.  We  had  thought  a  third  method  rmght  be  added,  namely, 
to  mix  with  the  bird's  food  some  anthelmintic,  which,  if  worms 
containing  the  embryos  were  eaten,  would  destroy  them  without 
injuring  the  fowl.  This  opinion  was  changed  after  the  experi- 
ments detailed  belowwere  concluded.  The  first  method  consists  in 
either  keeping  them  on  wooden  floors,  or  some  grassy  plot  or 
ground  where  the  disease  has  never  existed.  The  second  method, 
that  of  destroying  the  earthworm,  involves  the  question  as  to 
what  is  the  best  method  of  doing  this.  The  article  to  be  chosen 
must  be  cheap,  effective,  readily  applied,  and  safe  to  use.  We 
have  experimented  with  three  different  substances,  each  of  which 


23 

possesses  to  a  considerable  degree  these  qualities.  They  are 
common  salt  (chloride  of  sodium),  lime  (oxide  of  calcium),  and 
wood  ashes  (mostly  composed  of  potassa  and  its  carbonate).  In 
the  experiments  medium-sized  earthworms  were  used,  and  the 
embryos  of  Syngamits  were  taken  from  the  intestine  of  the  earth- 
worm. 

EXPERIMENTS   WITH   EARTHWORMS  AND   EMBRYOS 

OF  SYNGAMUS. 

Exp.  i.  An  earthworm  just  dug,  and  with  the  dirt  still  adher- 
ing to  it,  was  thrown  into  dry  lime  which  had  been  slacked  for 
several  weeks.    At  the  end  of  twelve  minutes  it  was  dead. 

Exp.  2.  Another  earthworm  was  thrown  into  linie  water;  in 
seven  minutes  it  ceased  to  move. 

Exp.  3.  An  embryo  of  Syngamits  trachealis  was  placed  in  lime 
water;  it  was  observed  for  two  hours,  at  the  end  of  which  time  it 
was  still  alive  and  active. 

Exp.  4.  An  earthworm  was  placed  in  a  solution  of  common 
salt  having  the  strength  of  one-fourth  pound  to  the  gallon  of 
water.    In  six  minutes  it  was  dead. 

Exp.  5.  An  embryo  of  Syngamus  placed  in  the  above  solu- 
tion lived  thirty-three  minutes. 

Exp.  6.  An  earthworm  placed  in  a  solution  of  salt  having  the 
strength  of  one-half  pound  to  the  gallon  of  water  lived  four 
minutes. 

Exp.  7.  An  embryo  of  Syngamus  placed  in  the  above  solu- 
tion ceased  to  move  in  fourteen  and  one-half  minutes. 

Exp.  8.  An  earthworm  placed  in  a  salt  solution  having  the 
strength  of  one  pound  to  one  gallon  of  water  lived  about  three 
minutes. 

Exp.  9.  An  Embryo  of  Syngamus  placed  in  the  above  solu- 
tion lived  three  minutes. 

Exp.  10.  An  earthworm  thrown  on  dry  salt  ceased  to  move 
in  somewhat  less  than  three  minutes. 

Exp.  11.  An  earthworm  thrown  on  dry  ashes  lived  a"bout 
twelve  minutes. 

Exp.  12.  An  earthworm  placed  in  lye  made  by  pouring  warm 
water  on  wood  ashes  and  letting  it  stand  one  hour,  the  proportion 
being  one-half  pound  of  ashes  to  one  gallon  of  water.  The  earth- 
worm ceased  to  move  in  three  minutes. 


24 

Exp.  13.  An  embryo  of  Syngamiis  placed  in  the  above  solu- 
tion was  apparently  unaffected  at  the  end  of  twelve  hours. 

Exp.  14.  An  embryo  of  Syngamiis  placed  in  a  watch  glass 
containing  a  mixture  of  water  and  asafoetida,  many  small  pieces 
of  the  latter  being  scattered  over  the  bottom.  At  the  end  of  one 
hour  it  was  unaffected,  although  almost  constantly  in  contact 
with  the  lumps  of  asafoetida. 

Exp.  15.  An  embryo  of  Syngamiis  placed  in  a  watch  glass 
with  water,  and  several  small  pieces  of  an  onion,  making  a  strong 
solution,  were  added  to  the  same.  At  the  end  of  six  hours  very 
little  abatement  in  the  vigor  of  its  movements  was  perceptible. 
In  twelve  hours  it  still  lived,  but  its  movements  were  very  slow. 

The  result  of  the  above  experiments  may  be  stated  as  follows: 
Lime,  salt,  and  ashes  are  all  effective  in  destroying  the  earthworm. 
Lime  water  and  lye  of  the  strength  used  seemed  to  have  very 
little  effect  on  the  embryo  of  Syngamiis.  Doubtless,  a  stronger 
solution  of  ashes  would  kill  it,  and  it  is  probable  that  lime  in 
substance  would  also  be  effective.  Salt  not  only  destroys  the 
earthworm,  but  it  also  kills  the  embryo  of  Syngamiis.  The  anthel- 
mintic power  of  asafoetida  and  the  onion  has  disappointed  us 
much.  The  latter  belongs  to  the  same  family  (Allium),  and  has 
similar  properties  to  garlic,  which  has  been  so  highly  recom- 
mended as  a  specific  in  the  gapes.  Ashes,  lime  or  salt  may  then 
be  used.  The  first  two  can  be  spread  over  the  ground.  Lime,  in 
the  form  of  lime  water,  is  exceedingly  cheap,  but,  exposed  to  the 
air,  or  in  the  soil  soon  combines  with  carbonic  acid,  forming  car- 
bonate of  lime,  which  is  probably  harmless  to  the  earthworm.  We 
believe  salt  is  more  reliable,  and  it  has  also  the  additional  ad- 
vantage of  destroying  the  embryo  of  the  gape  worm  in  the  soil. 
It  can  be  used  in  poultry  yards  in  the  proportion  of  one  pound  to 
the  gallon  of  water,  or,  if  the  soil  is  very  moist,  two  pounds  would 
be  better.  If  a  large  extent  of  ground  is  to  be  treated,  the  salt 
could  be  scattered  in  substance  over  the  surface  and  left  to  be 
dissolved  by  rain  or  plowed  under,  taking  care  that  none  of  it 
is  eaten  by  fowls.  This  method  has  been  adopted  by  setae  with 
success,  no  more  gapes  having  developed  in  their  chicks.  All 
poultry  dying  of  the  gapes  should  be  burned,  and  not  left  upon 
the  ground,  or  even  buried  deep,  as  advised  by  some,  for  the  eggs 
may  hatch,  and  the  embryos  be  taken  by  the  earthworm  to  the 
surface  to  propagate  the  disease. 


25 


CONCLUDING  REMARKS. 


Before  closing-,  we  wish  carefully  to  examine  a  few  points 
concerning  the  life  history  of  Syngamus  trachealis,  and  the  propa- 
gation of  the  gapes.  First,  do  fowls  contract  the  disease  by  pick- 
ing up  the  eggs,  or  mature  Syn  garni  containing  them?  Dr. 
Megnin's  parrot  was  claimed  to  have  taken  the  disease  from  eat- 
ing, on  August  7th,  four  mature  Syngami  filled  with  eggs.  The 
first  symptoms  of  the  gapes  manifested  themselves  on  August 
28th,  twenty-one  days  after  the  feeding,  and  the  bird  died  Sep- 
tember 10th,  on  the  thirteenth  day  of  the  disease.  We  believe  if 
the  eggs  were  retained  and  hatched  before  they  reached  the 
proventriculus,  the  gapes  would  result.  But  we  think  such  a  case 
is  exceptional,  and  not  the  way  in  which  the  disease  generally 
occurs.  In  proof  of  this  we  will  not  only  bring  forward  the  chick 
fed  mature  Syiigami  (see  feeding  exp.  11),  but  also,  the  general 
fact  that  chicks,  about  fourteen  days  after  they  take  in  the 
embryos  of  Syngamus,  have  large  quantities  of  mature  eggs  pass 
through  their  intestines  into  the  soil.  According  to  first  theory, 
these  eggs  should  hatch  within  the  chick;  it  would  thus  become 
self-infecting,  and  would  almost  necessarily  die.  On  the  con- 
trary, after  chicks  are  a  few  weeks  old  they  generally  recover, 
their  windpipes  being  large  so  that  the  usual  number  does  not 
very  materially  interfere  with  their  respiration.  That  the  eggs  are 
not  contained  in  the  earthworm  and  thus  taken  we  believe  is  true, 
for,  in  the  examination  of  very  many  infested  earthworms  during 
the  past  fourteen  years,  we  have  never  found  an  egg  of  Syngamus. 
It  is  also  evident  that  the  time  required  to  produce  the  gapes  by 
feeding  earthworms  is  too  short  for  the  eggs  to  hatch  and  the 
embryos  to  pass  through  their  different  stages.  Again,  the  eggs 
are  so  small  they  could  not  be  seen,  as  they  were  scattered  over 
the  ground,  and  picked  up  by  chicks,  and  it  is  highly  improbable 
that  they  would  retain  their  vitality  through  the  long  winter 
months  in  this  climate,  and  propagate  the  disease  in  chicks  the 
following  summer.  We  are  aware  that  the  eggs  of  various  in- 
sects survive  the  winter,  and  continue  their  species  from  year  to 
year,  but  we  have  found  by  experiment  that  the  eggs  of  Syngamus 
trachealis  will  not  hatch  after  being  kept  a  few  weeks,  fatty  de- 
generation takes  place,  and  their  vitality  is  destroyed.  We  con- 
sider it  unnecessary  to  bring  forward  further  proof  on  this  point. 
Dr.  Megnin  himself  abandons  the  theory,  and  says:  "The  birds 
are  infected  by  drinking  water  containing  the  embryos."    We  are 


26 

then  forced  to  the  conclusion  that  the  living-  embryo,  in  some 
manner,  finds  its  way  into  birds,  and  is  there  developed  into  the 
perfect  worm.  That  the  gapes  can  be  artificially  produced  by 
feeding  the  embryos  of  Syngamus  hatched  in  water  to  chicks,  we 
readily  admit,  for  we  have  proved  such  is  the  case  by  experiment 
13.  But  we  deny  that  this  is  the  natural  way  in  which  they  con- 
tract the  disease.  In  this  climate  of  ours,  with  a  long  severe 
winter,  the  thermometer  is  often  down  to  zero,  water,  when  re- 
maining on  the  surface  of  the  ground  would  be  frozen  a  hundred 
times,  and  during  the  warm  season  none  would  be  found  except 
in  rainy  weather.  How  then,  we  ask,  would  it  be  possible  for 
the  embryo  to  live  through  the  cold  season  in  water,  and  be  taken 
by  chicks  the  next  spring,  in  the  water  they  drink  from  the  sur- 
face of  the  ground.  Some  of  the  Nematoid  worms,  to  which  class 
Syngamus  belongs,  can  be  brought  to  maturity  by  being  taken  in 
water.  Nevertheless  they  have  intermediate  hosts  which  act  as  a 
bearer,  exactly  as  the  earthworm  acts  as  a  bearer  to  the  gape  worm. 
They  differ  from  most  of  the  tape  worms  which  have  to  pass 
through  an  intermediate  host,  in  which  they  are  partially  devel- 
oped, to  prepare  them  for  a  final  development  in  their  last  host. 
To  illustrate:  Trichinae  belong  to  the  Nematoid  worms,  the 
same  class  as  the  gape  worm,  and  could  be  propngated  in  man  by 
drinking  them  in  water,  but  did  you  ever  hear  of  this  taking  place 
in  nature?  No!  They  get  them  from  their  intermediate  host,  the 
hog.  The  question  is  not  what  might  happen,  but  what  does 
actually  occur  in  nature,  without  the  intervention  of  man.  I  do 
not  believe  the  Creator,  in  his  infinite  wisdom,  has  designed  that 
the  gape  worm  should  be  without  a  bearer,  for  you  can  easily 
perceive  what  would  become  of  the  poor  worm  in  these  Northern 
States  were  such  the  case.  The  soil  is  often  frozen  to  a  great 
depth,  and  it  would  be  utterly  destroyed.  Besides  this,  it  could 
not  be  picked  up  by  a  chick  or  bird,  except  by  the  merest  acci- 
dent, for  it  is  so  small  it  could  not  be  seen.  No!  this  is  not  so. 
It  has  been  wisely  decreed  that  the  earthworm  should  be  its  inter- 
mediate host,  in  the  intestine  of  which  it  finds  all  the  nourishment 
necessary  to  sustain  it.  When  winter  comes  it  is  carried  deep  into 
the  ground,  out  of  all  reach  of  cold,  and  in  the  spring  is  brought 
again  to  the  surface  ready  to  be  picked  up  in  the  earthworm,  and 
pass  through  the  remaining  portion  of  its  existence  in  its  final 
host,  the  fowl.  Now,  the  proof  is  positive,  and  must  be  acknowledged, 
that  earthworms  do  contain  the  embryos  of  Syngamus  trachealis,  and 


27 

that  the  gapes  can  be  produced  by  feeding  the  earthworms  containing 
them  to  chicks  (see  the  various  experiments  herein  detailed).  But, 
some  say  it  is  only  an  accidental  host  of  the  earthworm,  taken 
in  with  the  particles  of  earth,  leaves,  etc.,  while  boring  through 
the  soil,  and  that  the  embryos  may  even  be  used  as  food  by  the 
earthworm.  I  have  not  the  slightest  faith  in  its  being  an  acci- 
dental host  of  the  earthworm,  temporarily  taken  in  with  leaves, 
grass,  etc.,  or  used  as  food.  If  this  was  the  case,  why  should  we 
find  it,  as  I  have  often  done,  in  many  earthworms  in  an  infested 
locality,  in  midwinter,  down  deep  in  the  ground,  in  the  same  posi- 
tion as  in  summer,  in  the  intestine  of  the  earthworm?  Why  did 
it  not  pass  off  with  leaves  and  other  matter  used  as  food,  instead 
of  remaining  throughout  the  year?  I  have  found  twenty  in  a 
single  earthworm,  and  often  five  to  ten.  If  the  embryo  was  taken 
in  as  an  accidental  host,  I  see  no  reason  why  we  should  not  at 
times  find  some  of  the  eggs  of  Syngamus  in  the  earthworm,  but  as 
before  stated,  we  have  never  found  one.  In  all  our  study  of  the  life 
history  of  the  gape  worm,we  have  never  found  any  way  in  nature ^with- 
out the  intervention  of  man,  through  which  they  obtained  access  to  birds, 
except  the  earthworm.  There  is  no  food  more  natural  for  fowls 
than  these.  Chicks,  two  days  old,  eat  them  greedily.  No  embryos 
of  Syngamus  have  ever  been  discovered,  on  repeated  examinations, 
in  any  other  forms  of  animal  life  about  the  coops  of  chicks  having  the 
gapes,  except  earthworms.  These  examinations  were  made  with 
the  microscope,  and  also  by  feeding  experiments  with  chicks.  No 
embryos  like  those  of  Syngamus,  were  found  in  earthworms  which 
did  not  produce  the  gapes  by  feeding  them  to  chicks.  /  have  made 
inquiries  in  various  parts  of  our  country,  where  no  earthworms  are 
found,  as  to  the  existence  of  gapes,  and  have  invariably  received  the 
reply  that  their  fozvls  do  not  have  the  disease.  The  robin  and  other 
worm-eating  birds  which  act  as  hosts  for  Syngamus,  without 
question  disseminate  the  disease  from  one  farm  or  part  of  the 
country  to  another.  When  you  remove  your  chicks  to  new 
ground  where  there  has  never  been  any  gapes,  the  earthworms 
will  not  contain  the  embryos,  and  your  chicks  will  be  free  from 
the  disease.  This  has  been  demonstrated  many  times  in  this 
vicinity.  Also,  the  fact  that  using  a  strong  solution  of  salt  on  the 
ground,  and  thus  killing  the  infested  earthworms  about  coops 
where  chicks  have  previously  had  the  disease,  would  entirely  pre- 
vent any  outbreak  the  following  year.  It  is  a  matter  of  common 
observation,  that  the  gapes  is  more  prevalent  during  wet  seasons, 


28 

than  dry  ones.  This  is  easily  explained;  the  reason  being  that 
earthworms  are  more  plenty  on  the  surface  of  the  ground,  where 
they  are  easily  picked  up  by  chicks.  It  is  also  well  known  that 
when  chicks  are  let  out  in  the  early  morning,  they  are  more  apt 
to  have  the  gapes.  This  was  thought  by  many  to  result  from  their 
getting  wet  and  cold,  but  it  is  easily  explained  by  their  finding  the 
earthworms  out  at  that  time,  when  if  they  were  not  let  out  until 
the  moisture  was  dried  off  the  ground,  the  earthworms  could  not 
be  found,  they  had  retired  into  their  burrows.  The  old  adage, 
"The  early  bird  catches  the  worm,"  well  illustrates  this  point.  It 
is  also  a  well-known  fact  that  chicks  kept  near  a  chip  yard,  were 
apt  to  have  the  gapes.  This  is  readily  explained  by  reason  of 
their  easily  getting  earthworms  by  scratching  the  chips  from  the 
surface  of  the  ground,  earthworms  being  found  plenty  in  such 
places. 

FINALLY,  THERE  IS  NOTHING  CONNECTED  WITH 
THE  GAPES  WHICH  CANNOT  BE  FULLY,  AND  CLEAR- 
LY EXPLAINED  THROUGH  THE  AGENCY  OF  EARTH- 
WORMS. 

We  will  recapitulate  the  several  points  we  consider  established 
by  this  investigation.  First,  that  the  earthworm  is  the  inter- 
mediate host  of  Syngamus  trachcalis,  is  proved  by  many  successful 
experiments  in  feeding  them  to  chicks.  None  of  the  chicks  fed 
earthworms  from  an  infected  spot,  failed  to  have  the  gapes  in 
seven  days.  On  microscopic  examination,  the  embryos  of 
Syngamus  were  found  in  these  earthworms.  That  no  other  forms 
of  animal  life  about  the  coops  act  as  a  host  for  Syngamus,  proved 
by  feeding  all  those  found  to  chicks  and  they  failed  to  produce 
the  gapes;  also,  none  of  the  embryos  were  found  in  them  on  ex- 
amination with  the  microscope.  That  all  earthworms  do  not  con- 
tain the  embryos  of  Syngamus,  proved  by  feeding  three  chicks 
earthworms  from  a  place  where  no  gapes  existed.  They  failed  to 
have  the  gapes,  rind  no  embryos  of  Syngamus  could  be  found  in 
the  earthworms  with  the  microscope.  That  the  earthworm  is 
only  a  bearer,  or  means  of  conveying  the  embryo  to  the  fowl,  is 
proved  by  feeding" the  embryos  hatched  from  the  eggs  to  a  chick, 
and  thus  producing  the  gapes.  Also,  the  fact  that  the  embryos 
in  the  earthworm  do  not  develop,  either  in  growth  or  structure, 
more  than  when  they  emerged  from  the  tgg.  That  the  embryo 
of  Syngamus  is  not  an  accidental  host  of  the  earthworm,  proved 
by  finding  them  in  considerable  numbers,  in  main  earthworms, 


29 

in  an  infected  spot,  throughout  the  year.     No  earthworms,  no 
gapes.    This  view  is  supported  by  inquiries  made  in  various  parts 
of  the  country  where  there  are  no  earthworms,  in  which  places, 
they  say  the  fowls  do    not    have    the    gapes.     The    embryo  of 
Syngamus  has  been  found  in  the  earthworm,  and  identified  by 
tracing  it  through  its  different  stages  from  the  earthworm  to  the 
trachea  of  the  chick,  and  also  by  artificial  culture.    That  they  pass 
through  the  esophagus  of  the  chick  is  demonstrated  by  finding 
them  beneath   its  mucous  membrane,   and  just  after  they   had 
passed  through  into  the  lungs;  also,  by  finding  the  esophagus 
adherent  to  the  lungs  in  many  chicks  which  had  the  gapes,  this 
condition  not  being  found  in  those  which  did  not  have  this  disease. 
That  the  disease  is  transmitted  from  one  year  to  another  by  drink- 
ing water  containing  the  embryos,  is  rendered  impossible  in  a  cold 
climate,  where  the  water  is  frozen  many  times  during  the  winter, 
and  often  dried  from  the  surface  in  the  summer.    That  the  robin 
(Turdus    migratorius),   and   probably   many   other   worm-eating 
birds  may  act  as  a  host  for  Syngamus,  and  thus  be  instrumental 
in  spreading  the  disease,  is  proved  by  feeding  three  robins  and 
finding  full-grown  worms  in  their  tracheas.     That  the  union  be- 
tween the  genital  organs  of  the  male  and  female  is  incomplete  at 
its  posterior  part,  so  that  the  eggs  can  be,  and  are  readily  ex- 
pelled during  the  life  of  the  worm,  proved,  by  seeing  this  take 
place  under  the  microscope.     That  the  mature  Syngamus,  while 
yet  in  the  trachea  of  the  fowl,  lays  its  eggs,  which  are  coughed  up, 
swallowed,  and  pass  through  the  intestines  of  the    fowl  to    the 
ground.     Proved,  by  finding  the  eggs  in  the  excretions,  and  the 
living  worms  from  which  eggs  were  passing,  in  the  trachea.  That 
the  genital  organs  of  the  sexes  are  not  grown  together,  proved, 
by  separating  them  without  rupture,  and  finding  them  to  adhere 
by  means  of  suckers  on  the  genital  organs  of  the  male.    That  the 
mature  egg  does  not  contain  an  embryo  is  proved  by  examining 
them  after  they  are  naturally  expelled  by  Syngamus,  and  finding 
that  two  or  three  weeks  are  required  for  the  embryo  to  develop  in 
them.     That  the  embryo  of  Syngamus  is  but  slightly  affected  by 
the  anthelmintics  which  have  been  used  to  prevent  and  cure  the 
disease,  as  asafoetida  and  garlic.     They  cannot  be  relied  on  for 
this  purpose.     Lastly,   to  prevent  your  fowls   from  having  the 
gapes,  remove  them  to  some  spot  where  the  disease  has  never 
existed,  or  destroy  the  infested  earthworms  in  the  ground  with 
common  salt. 


30 

The  life  history  of  Syngamus  trachealis  is  as  follows:  Earth- 
worms containing  the  embryos  are  eaten  by  the  fowl.  The 
embryos  are  liberated  from  the  intestine  of  the  earthworm  and 
work  their  way  through  the  esophagus  into  the  lungs  and  bronchi. 
Here  they  pass  through  the  nymph  stage  and  acquire  sexual 
maturity.  The  male  and  female  then  unite,  work  their  way  into 
the  trachea,  and  attach  themselves  to  its  mucous  membrane  by 
their  sucker-like  mouths.  Between  six  and  seven  days  are  re- 
quired from  its  entrance  into  the  fowl  until  its  attachment  to  the 
trachea.  In  about  seven  days  more  the  eggs  within  the  body  of 
the  worm  become  mature.  They  are  coughed  up  into  the  mouth, 
swallowed  by  the  fowl,  and  pass  through  it  into  the  soil.  In  about 
three  weeks,  the  time  varying  somewhat  according  to  the  tem- 
perature, these  eggs,  exposed  to  the  moisture  and  sun,  hatch ;  the 
embryos  are  taken  in  their  food  by  the  earthworm,  where  they 
remain  until  picked  up  by  some  bird,  when  the  above  process  is 
repeated.  Some  years  one-half  or  two-thirds  of  the  young  fowls 
in  certain  localities  are  destroyed  by  this  disease.  This  investiga- 
tion proves  that  if  they  were  kept  from  eating  infested  earth- 
worms, that  terrible  scourge  of  poultry,  the  gapes,  would  be  en- 
tirely prevented.  Not  only  this,  but  it  serves  as  a  key  to  unlock 
the  mysteries  surrounding  several  other  diseases,  caused  by  para- 
sites belonging  to  this  family;  namely,  the  lung  worm  of  calves 
(Strongylus  micrariis),  the  lung  worm  of  hogs  (Strongylus  cb'iga- 
tus),  the  lung  worm  of  sheep  (Strongylus  filiaria),  the  grouse 
disease  (Strongylus  pcrgracilis).  Great  numbers  of  calves,  hogs, 
sheep  and  grouse  are  yearly  destroyed  by  these  parasites.  Their 
intermediate  hosts  have  never  been  discovered.  From  certain 
inquiries  which  I  have  made,  I  venture  to  predict  that  the  earth- 
worm will  be  found  to  be  their  intermediate  host.* 


*Cobbold  in  hi?  work  on  "  Parasites,"  page  336-346,  after  a  series  of  observations  states 
his  belief  that  the  earthworm  may  act  as  an  intermediate  host  for  Strongylus  micrurw. 


' 


r'jfr.-* 


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